Aberrations of TACC1 and TACC3 are associated with ovarian cancer

Tubulin Complexity in Cancer and Metastasis

Tubulin plays a fundamental role in cellular function and as the subject for microtubule-active agents in the treatment of ovarian cancer. Microtubule-binding proteins (e.g., tau, MAP1/2/4, EB1, CLIP, TOG, survivin, stathmin) and posttranslational modifications (e.g., tyrosination, deglutamylation, acetylation, glycation, phosphorylation, polyamination) further diversify tubulin functionality and may permit additional opportunities to understand microtubule behavior in disease and to develop microtubule-modifying approaches to combat ovarian cancer. Tubulin-based structures that project from suspended ovarian cancer cells known as microtentacles may contribute to metastatic potential of ovarian cancer cells and could represent an exciting novel therapeutic target.

TACC3: a multi-functional protein promoting cancer cell survival and aggressiveness

TACC3 is the most oncogenic member of the transforming acidic coiled-coil domain-containing protein (TACC) family. It is one of the major recruitment factors of distinct multi-protein complexes. TACC3 is localized to spindles, centrosomes, and nucleus, and regulates key oncogenic processes, including cell proliferation, migration, invasion, and stemness. Recently, TACC3 inhibition has been identified as a vulnerability in highly aggressive cancers, such as cancers with centrosome amplification (CA). TACC3 has spatiotemporal functions throughout the cell cycle; therefore, targeting TACC3 causes cell death in mitosis and interphase in cancer cells with CA. In the clinics, TACC3 is highly expressed and associated with worse survival in multiple cancers. Furthermore, TACC3 is a part of one of the most common fusions of FGFR, FGFR3-TACC3 and is important for the oncogenicity of the fusion. A detailed understanding of the regulation of TACC3 expression, its key partners, and molecular functions in cancer cells is vital for uncovering the most vulnerable tumors and maximizing the therapeutic potential of targeting this highly oncogenic protein. In this review, we summarize the established and emerging interactors and spatiotemporal functions of TACC3 in cancer cells, discuss the potential of TACC3 as a biomarker in cancer, and therapeutic potential of its inhibition.

Elevated expression of transforming acidic coiled-coil-containing protein 3 (TACC3) reflects aggressiveness of primary central nervous system lymphomas

Transforming acidic coiled-coil-containing protein 3 (TACC3) plays an important role in centrosome/microtubule dynamics. Deregulation of centrosomes/microtubules causes mitotic spindle defects, leading to tumorigenesis. However, the correlation between TACC3 and primary central nervous system lymphomas (PCNSLs) is unknown. The present study investigated the association between the immunohistochemical expression of TACC3, p53, and Ki-67, and the clinical factors in 40 PCNSLs. We evaluated the staining of TACC3 based on the histoscore (H-score) that contains a semiquantitative evaluation of both the intensity of staining, and the percentage of positive cells. Expression level of each component was classified as low or high according to the median H-score value. Patients with PCNSLs were divided into groups depending on TACC3 expression levels (no expression and low expression, 18; high expression, 22). Disease-free survival and overall survival of patients with high TACC3 expression were significantly shorter (p < 0.01 and p < 0.05, respectively). These results suggest that elevated expression of TACC3 could reflects aggressiveness of primary central nervous system lymphomas.

LINC01140 inhibits nonsmall cell lung cancer progression and cisplatin resistance through the miR-4742-5p/TACC1 axis

Recent studies show that lncRNAs participate in drug resistance and nonsmall cell lung cancer (NSCLC) progression. This study aimed to study the roles and mechanisms of long intergenic nonprotein coding RNA 01140 (LINC01140) in regulating NSCLC progression and drug resistance. Real-time quantitative polymerase chain reaction and western blot analysis were used to detect LINC01140, miR-4742-5p, and transforming acidic coiled-coil 1 (TACC1) expression in NSCLC cells. The interaction between two molecules was examined by luciferase reporter and/or RNA immunoprecipitation assays. Cell invasion, apoptosis, and cisplatin cytotoxicity were assessed by transwell invasion assay, flow cytometry analysis, and CCK-8 assay, respectively. LINC01140 was downregulated and miR-4742-5p was upregulated in NSCLC. LINC01140 inhibited miR-4742-5p expression by competitively binding to miR-4742-5p, while miR-4742-5p targeted TACC1 to inhibit TACC1 expression in NSCLC cells. LINC01140 enrichment repressed the invasive potential and cisplatin resistance and triggered apoptosis, which was reversed by miR-4742-5p overexpression. miR-4742-5p inhibition suppressed cell invasion and cisplatin resistance and accelerated apoptosis in NSCLC cells, while TACC1 silencing abolished these effects. Mechanistically, LINC01140 positively regulated TACC1 expression by sponging miR-4742-5p. In conclusion, LINC01140 inhibited NSCLC progression and cisplatin resistance via functioning as a ceRNA for miR-4742-5p to modulate TACC1.

A Genome-Wide Investigation of Effects of Aberrant DNA Methylation on the Usage of Alternative Promoters in Hepatocellular Carcinoma

BACKGROUND

The alternative usage of promoters provides a way to regulate gene expression, has a significant influence on the transcriptome, and contributes to the cellular transformation of cancer. However, the function of alternative promoters (APs) in hepatocellular carcinoma (HCC) has not been systematically studied yet. In addition, the potential mechanism of regulation to the usage of APs remains unclear. DNA methylation, one of the most aberrant epigenetic modifications in cancers, is known to regulate transcriptional activity. Whether DNA methylation regulates the usage of APs needs to be explored. Here, we aim to investigate the effects of DNA methylation on usage of APs in HCC.

METHODS

Promoter activities were calculated based on RNA-seq data. Functional enrichment analysis was implemented to conduct GO terms. Correlation tests were used to detect the correlation between promoter activity and methylation status. The LASSO regression model was used to generate a diagnostic model. Kaplan-Meier analysis was used to compare the overall survival between high and low methylation groups. RNA-seq and whole-genome bisulfite sequencing (WGBS) in HCC samples were performed to validate the correlation of promoter activity and methylation.

RESULTS

We identified 855 APs in total, which could be well used to distinguish cancer from normal samples. The correlation of promoter activity and DNA methylation in APs was observed, and the APs with negative correlation were defined as methylation-regulated APs (mrAPs). Six mrAPs were identified to generate a diagnostic model with good performance (AUC = 0.97). Notably, the majority of mrAPs had CpG sites that could be used to predict clinical outcomes by methylation status. Finally, we verified 85.6% of promoter activity variation and 92.3% of methylation changes in our paired RNA-seq and WGBS samples, respectively. The negative correlation between promoter activity and methylation status was further confirmed in our HCC samples.

CONCLUSION

The aberrant methylation status plays a critical role in the precision usage of APs in HCC, which sheds light on the mechanism of cancer development and provides a new insight into cancer screening and treatment.

Loss of TACC1 variant25 inducing cell proliferation and suppressing autophagy in head and neck squamous carcinoma

Transforming acidic coiled-coil containing protein1 (TACC1) is closely related to transcription, translation and centrosome dynamics. Dysregulation of TACC1 is associated with multiple malignancies. Alternative splicing (AS) of TACC1 produces multiple variants, which are of great significance in cancer biology. However, the expression and biological functions of TACC1 variants in head and neck squamous cell carcinoma (HNSCC) remain unclear. In this study, we found for the first time that TACC1 variants exhibited a characteristic expression pattern and that TACC1 variant25 (TACC1v25) was downregulated in HNSCC tissues and cell lines. Overexpression of TACC1v25 in Cal27 and Fadu cells significantly inhibited proliferation and promoted autophagy. Moreover, expression levels of nuclear pERK and p-mTOR were significantly decreased, while the expression of Beclin-1 and the LC3II/LC3I ratio were increased in TACC1v25-overexpressed Cal27 and Fadu cells. After the addition of AKT activator SC79 to TACC1v25-overexpressed Cal27 and Fadu cells, the autophagy levels were remarkably rescued. In conclusion, TACC1v25 inhibits HNSCC progression through the ERK and AKT/mTOR pathways by inhibiting proliferation and increasing autophagy. TACC1v25 might have potential use as a tumour suppressor in HNSCC.

Increased expression levels of AURKA and KIFC1 are promising predictors of progression and poor survival associated with gastric cancer

Increased cell proliferation is a critical hallmark of cancer development and progression. The proliferation of tumor cells depends on mitotic deregulation. Here, we identified the differentially expressed genes (DEGs) in gastric cancer (GC) through RNA sequencing data and bioinformatics analysis. Subsequent functional and pathway enrichment analyses showed that the screened DEGs were enriched in the mitosis-associated pathway. Based on the analysis results, we selected two signatures (aurora kinase A [AURKA] and kinesin family member C1 [KIFC1]) to determine their clinicopathological significance. The results showed a significant positive correlation between AURKA and KIFC1 expression both at the mRNA and protein levels. AURKA expression was positively correlated with distant metastases (p = 0.032) and tumor-node-metastasis (TNM) stage (p = 0.001). Elevated KIFC1 expression was significantly associated with tumor size (p = 0.029), depth of invasion (p < 0.001), lymph node metastasis (p < 0.001), distant metastasis (p = 0.023), and TNM stage (p < 0.001). Higher AURKA (hazard ratio [HR] = 1.3, p < 0.001) and KIFC1 (HR = 1.41, p < 0.001) mRNA levels were also significantly correlated with poor overall survival. Thus, AURKA and KIFC1 could serve as potential prognostic markers and therapeutic targets for GC.

Transforming acidic coiled-coil protein-3: a novel marker for differential diagnosis and prognosis prediction in endocervical adenocarcinoma

Background

Endocervical adenocarcinoma (ECA) is further classified as human papillomavirus (HPV)-associated (HPVA) or non-HPVA (NHPVA), per the International Endocervical Adenocarcinoma Criteria and Classification (IECC). HPVA is a glandular tumor with stromal invasion and/or exophytic expansile-type invasion, associated with the typical molecular characteristics of high-risk HPV (HR-HPV) infection. Transforming acidic coiled-coil protein-3 (TACC3),an oncogene that is frequently abnormally expressed,represents a vital biomarker for multiple human malignancies. This study aimed to examine the role of TACC3 in the diagnosis and prognosis of ECA.

Methods

We analyzed 264 patients with ECA who underwent surgical resection, classifying their tumors into HPVA and NHPVA subtypes. The expression levels of TACC3, P16, MLH1, PMS2, MSH2, MSH6 and Ki-67 in tumors were evaluated by tissue microarray using immunohistochemistry (IHC). HPV subtypes were identified in formalin-fixed paraffin-embedded (FFPE) ECA tissues by the polymerase chain reaction (PCR).

Results

ECA samples showed increased TACC3 expression relative to adjacent non-carcinoma samples. TACC3 expression was higher in HPVA than in NHPA. In the HPVA subtype, high TACC3 expression was significantly correlated with P16-positive, Ki-67-high expression. Furthermore, TACC3 levels were significantly related to tumor histological type (P = 0.006), nerve invasion (P = 0.003), differentiation (P = 0.004), surgical margin (P = 0.012), parametrium invasion (P = 0.040), P16 expression (P < 0.001), and Ki-67 (P = 0.004). Additionally, Kaplan–Meier analysis showed that TACC3 upregulation was associated with poor overall survival (OS, P = 0.001), disease-free survival (DFS, P < 0.001), and recurrence survival (P < 0.001). Multivariate analysis indicated that elevated TACC3 expression served as a marker to independently predict ECA prognosis. ROC curve analyses indicated that TACC3, P16, and HPV subtypes showed similar utility for distinguishing HPVA from NHPVA, with areas under the ROC curves of 0.640, 0.649, and 0.675, respectively. The combination of TACC3 and HPV subtypes improved the diagnostic performance of ECA compared with TACC3, P16, and HPV subtypes alone.

Conclusions

Taken together, our findings identify that TACC3 is a promising complementary biomarker for diagnosis and prognosis for patients with ECA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00298-z.

Inhibiting of TACC3 Promotes Cell Proliferation, Cell Invasion and the EMT Pathway in Breast Cancer

Accumulating evidences indicate that transforming acidic coiled-coil 3 (TACC3) is a tumor-related gene, was highly expressed in a variety of human cancers, which is involved in cancer development. However, the potential role of TACC3 in breast cancer remains largely unknown. In the present study, we found that TACC3 was highly-expressed in breast cancer tissues, and its level was positively correlated with the clinical features of breast cancer patients. Specifically, TACC3 expression was significantly associated with the estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) status, nodal status, the scarff-bloom-richardson (SBR) grade, nottingham prognostic index (NPI), age, subtypes, and triple-negative and basal-like status, suggesting that TACC3 may be a potential diagnostic indicator of breast cancer. Furthermore, functional studies have shown that inhibition of TACC3 can significantly promote the cell proliferation and viability of breast cancer cells. Moreover, TACC3 knockdown suppressed the expression of E-cadherin, but increased the expression of N-cadherin, Snail, ZEB1, and TWIST, which indicate that TACC3 may impact the migration of breast cancer cells in vitro. Taken together, these findings indicate that TACC3 may serve as a prognostic and therapeutic indicator of breast cancer.

Primary Cilia, Ciliogenesis and the Actin Cytoskeleton: A Little Less Resorption, A Little More Actin Please

Primary cilia are microtubule-based organelles that extend from the apical surface of most mammalian cells, forming when the basal body (derived from the mother centriole) docks at the apical cell membrane. They act as universal cellular "antennae" in vertebrates that receive and integrate mechanical and chemical signals from the extracellular environment, serving diverse roles in chemo-, mechano- and photo-sensation that control developmental signaling, cell polarity and cell proliferation. Mutations in ciliary genes cause a major group of inherited developmental disorders called ciliopathies. There are very few preventative treatments or new therapeutic interventions that modify disease progression or the long-term outlook of patients with these conditions. Recent work has identified at least four distinct but interrelated cellular processes that regulate cilia formation and maintenance, comprising the cell cycle, cellular proteostasis, signaling pathways and structural influences of the actin cytoskeleton. The actin cytoskeleton is composed of microfilaments that are formed from filamentous (F) polymers of globular G-actin subunits. Actin filaments are organized into bundles and networks, and are attached to the cell membrane, by diverse cross-linking proteins. During cell migration, actin filament bundles form either radially at the leading edge or as axial stress fibers. Early studies demonstrated that loss-of-function mutations in ciliopathy genes increased stress fiber formation and impaired ciliogenesis whereas pharmacological inhibition of actin polymerization promoted ciliogenesis. These studies suggest that polymerization of the actin cytoskeleton, F-actin branching and the formation of stress fibers all inhibit primary cilium formation, whereas depolymerization or depletion of actin enhance ciliogenesis. Here, we review the mechanistic basis for these effects on ciliogenesis, which comprise several cellular processes acting in concert at different timescales. Actin polymerization is both a physical barrier to both cilia-targeted vesicle transport and to the membrane remodeling required for ciliogenesis. In contrast, actin may cause cilia loss by localizing disassembly factors at the ciliary base, and F-actin branching may itself activate the YAP/TAZ pathway to promote cilia disassembly. The fundamental role of actin polymerization in the control of ciliogenesis may present potential new targets for disease-modifying therapeutic approaches in treating ciliopathies.

TACC3 promotes prostate cancer cell proliferation and restrains primary cilium formation

Although primary cilia abnormalities have been frequently observed in multiple cancers, including prostate cancer (PCa), the molecular mechanisms underlying primary ciliogenesis repression in PCa cells remain unclear. Transforming acidic coiled-coil protein-3 (TACC3), whose deregulation has been implicated in the pathogenesis of several types of cancer, is a key centrosomal protein that plays a crucial role in centrosome/microtubule dynamics, potentially impacting primary cilium generation. Here, we showed that TACC3 was markedly upregulated in PCa and that knockdown of TACC3 restrained tumorigenesis and tumor growth in vitro and in vivo. Additionally, we found that TACC3 interacts with filamin A, and elevated levels of TACC3 disrupted the interaction between filamin A and meckelin, thereby restraining primary cilium formation in PCa cells.

Degradation of proteins by PROTACs and other strategies

Blocking the biological functions of scaffold proteins and aggregated proteins is a challenging goal. PROTAC proteolysis-targeting chimaera (PROTAC) technology may be the solution, considering its ability to selectively degrade target proteins. Recent progress in the PROTAC strategy include identification of the structure of the first ternary eutectic complex, extra-terminal domain-4-PROTAC-Von-Hippel-Lindau (BRD4-PROTAC-VHL), and PROTAC ARV-110 has entered clinical trials for the treatment of prostate cancer in 2019. These discoveries strongly proved the value of the PROTAC strategy. In this perspective, we summarized recent meaningful research of PROTAC, including the types of degradation proteins, preliminary biological data in vitro and in vivo, and new E3 ubiquitin ligases. Importantly, the molecular design, optimization strategy and clinical application of candidate molecules are highlighted in detail. Future perspectives for development of advanced PROTAC in medical fields have also been discussed systematically.

Pretreatment TACC3 expression in locally advanced rectal cancer decreases the response to neoadjuvant chemoradiotherapy

Chemoradiotherapy combined with surgical resection is the standard treatment for locally advanced rectal cancer, but not all the patients respond to neoadjuvant treatment. Transforming acidic coiled-coil protein-3 (TACC3) is frequently aberrantly expressed in rectal cancer tissue. In this study, we investigated whether TACC3 could serve as a biomarker predictive of the efficacy of chemoradiotherapy. In all, 152 rectal cancer patients with tumor tissue collected at biopsy and set aside before treatment were enrolled in this study. All patients received chemoradiotherapy and surgical resection. Immunohistochemically detected tumoral TACC3 expression significantly decreased sensitivity to chemoradiotherapy [risk ratio (RR) = 2.236, 95% confidence interval (CI): 1.447-3.456; P = 0.001] and thus the pathological complete response rate (P = 0.001). TACC3 knockdown using specific siRNA enhanced radiotherapy-induced decreases in proliferation and colony formation by HCT116 and SW480 cells and increased the incidence of radiotherapy-induced apoptosis. Cox multivariate analysis showed that TACC3 was a significant prognostic factor for overall survival (P = 0.017) and disease-free survival (P = 0.020). These findings suggest TACC3 expression may be predictive of chemoradiotherapy sensitivity and prognosis in locally advanced rectal cancer.

Progress on small-molecule proteolysis-targeting chimeras

Proteolysis-targeting chimeras (PROTACs) have received much attention for their promising therapeutic intervention in recent years. These molecules, with the mechanism of simultaneous recruitment of target protein and an E3 ligase, can trigger the cellular ubiquitin–proteasome system to degrade the target proteins. This article systematically introduces the mechanism of small-molecule PROTACs, and summarized the research progress of small-molecule PROTACs. The prospect for further application and the problems to be solved are also discussed.

High expression of TACC2 in hepatocellular carcinoma is associated with poor prognosis

BACKGROUND:

Transforming acidic coiled-coil protein 2 (TACC2) is a member of TACC family proteins which is mainly involved in the stabilization of spindles and regulation of microtubule dynamics through interactions with molecules involved in centrosomes/microtubules. TACC2 is involved in tumorigenesis of variety of cancers but the clinical significance of TACC2 protein in hepatocellular carcinoma (HCC) is still unclear.

OBJECTIVE:

This study aims to investigate the expression of TACC2 in HCC and determine if clinical significance and prognostic relevance exists.

METHODS:

We performed quantitative PCR (qPCR) and western blot to examine TACC2 mRNA and protein expression in paired HCC tissues and matched adjacent non-cancerous tissues. Immunohistochemistry was performed in 106 postoperative HCC samples.

RESULTS:

There was higher expression of TACC2 protein and mRNA in HCC tissue. Immunohistochemistry analysis showed high expression of TACC2 in HCC tissue and was significantly associated with the capsular extension, tumor recurrence and shortened overall and disease free survival. The Cox regression analysis suggested that a high expression of TACC2 was an independent prognostic factor for HCC patients.

CONCLUSION:

This finding suggests that TACC2 may be a useful tool as a candidate biomarker to predict the recurrence and prognosis of HCC.

Downregulation of TACC3 inhibits tumor growth and migration in osteosarcoma cells through regulation of the NF-κB signaling pathway

TACC3, a member of the transforming acidic coiled-coil protein (TACC) family, is a multifunctional protein that is involved in various biological functions, including proliferation and differentiation of tumor cells, cancer progression and metastasis. The aims of the present study were to examine whether TACC3 expression is associated with the proliferation and migration of osteosarcoma (OS) cells and to investigate the potential underlying molecular mechanisms of TACC3 in OS. First, the levels of mRNA and protein expression in OS cell lines by reverse transcription-quantitative polymerase chain reaction and western blotting, respectively were examined. Second, the effects of TACC3 knockdown and overexpression on the proliferative, migratory and invasive capacities of OS cells were investigated. Finally, western blot analysis was employed to detect the potential mechanism of TACC3 in osteosarcoma. TACC3 expression was significantly increased in osteosarcoma tissues and cell lines, compared to matched controls. The knockdown of TACC3 was able to significantly inhibit the proliferation, migration and invasion of osteosarcoma cells, whereas the overexpression of TACC3 was able to promote cell proliferation and migration. Mechanistically, TACC3 may promote the migration and invasion of osteosarcoma cells via through nuclear factor-κB signaling. These data suggest that TACC3 has an important part in the progression of osteosarcoma and may serve as a potential target for gene therapy.

TACC3 overexpression in cholangiocarcinoma correlates with poor prognosis and is a potential anti-cancer molecular drug target for HDAC inhibitors

Histone deacetylases (HDACs) have been implicated in multiple malignant tumors, and HDAC inhibitors (HDACIs) exert anti-cancer effects. However, the expression of HDACs and the anti-tumor mechanism of HDACIs in cholangiocarcinoma (CCA) have not yet been elucidated. In this study, we found that expression of HDACs 2, 3, and 8 were up-regulated in CCA tissues and those patients with high expression of HDAC2 and/or HDAC3 had a worse prognosis. In CCA cells, two HDACIs, trichostatin (TSA) and vorinostat (SAHA), suppressed proliferation and induced apoptosis and G2/M cycle arrest. Microarray analysis revealed that TACC3 mRNA was down-regulated in CCA cells treated with TSA. TACC3 was highly expressed in CCA tissues and predicted a poor prognosis in CCA patients. TACC3 knockdown induced G2/M cycle arrest and suppressed the invasion, metastasis, and proliferation of CCA cells, both in vitro and in vivo. TACC3 overexpression reversed the effects of its knockdown. These findings suggest TACC3 may be a useful prognostic biomarker for CCA and is a potential therapeutic target for HDACIs.

TACC3 transcriptionally upregulates E2F1 to promote cell growth and confer sensitivity to cisplatin in bladder cancer

Accumulating evidence has shown that transforming acidic coiled-coil 3 (TACC3) is deregulated in a broad spectrum of cancers. In the present study, we reported that TACC3 was markedly elevated in bladder cancer, especially in muscle-invasive bladder cancers (MIBCs). The upregulation of TACC3 was positively associated with tumor invasiveness, grade, T stage, and progression in patients with bladder cancer. Furthermore, a Kaplan-Meier survival analysis showed that patients with bladder cancer whose tumors had high TACC3 expression experienced a dismal prognosis compared with patients whose tumors had low TACC3 expression. Functional studies have found that TACC3 is a prerequisite for the development of malignant characteristics of bladder cancer cells, including cell proliferation and invasion. Moreover, TACC3 promoted G1/S transition, which was mediated via activation of the transcription of E2F1, eventually enhancing cell proliferation. Notably, the overexpression of TACC3 or E2F1 indicates a high sensitivity to cisplatin. Taken together, these findings define a tumor-supportive role for TACC3, which may also serve as a prognostic and therapeutic indicator in bladder cancers.

TACC3 promotes colorectal cancer tumourigenesis and correlates with poor prognosis

Colorectal carcinoma (CRC) is a malignant epithelial tumour with tremendous invasion and metastatic capacity. Transforming acidic coiled-coil protein-3 (TACC3), a frequently aberrantly expressed oncogene, is an important biomarker in various human cancers. Our study aimed to investigate the expression and function of TACC3 in human CRC. We found that TACC3 was over-expressed at both the mRNA and protein levels in CRC cells and in biopsies of CRC tissues compared with normal controls as determined by qRT-PCR, western blot and immunohistochemical (IHC) staining assays. IHC staining of samples from 161 patients with CRC also revealed that TACC3 expression was significantly correlated with clinical stage (P = 0.045), T classification (P = 0.029) and M classification (P = 0.020). Multivariate analysis indicated that high TACC3 expression was an independent prognostic marker for CRC. Patients who had high TACC3 expression had significantly poorer overall survival (OS, P = 0.023) and disease-free survival (DFS, P = 0.019) compared to patients who had low TACC3 expression. Furthermore, TACC3 knockdown attenuated CRC cell proliferation, colony formation capability, migration and invasion capability, and tumourigenesis in nude mice; these properties were measured using a real-time cell analyser (RTCA), clonogenicity analysis, and transwell and xenograft assays, respectively. These data indicate that TACC3 promotes CRC progression and could be an independent prognostic factor and a potential therapeutic target for CRC.

TACC3 as an independent prognostic marker for solid tumors: a systematic review and meta-analysis

Recent studies have showed that the transforming acidic coiled coil 3 (TACC3), was aberrantly up-regulated in various solid tumors and was reported to be correlated with unfavorable prognosis in cancer patients. This study aimed to examine the relationship between TACC3 and relevant clinical outcomes. Pubmed, Web of Science, Embase and Cochrane Library were systematically searched to obtain all eligible articles. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated to evaluate the influence of TACC3 expression on overall survival (OS) and disease-free survival (DFS) in solid tumors patients. A total of 1943 patients from 11 articles were included. The result indicated that a significantly shorter OS was observed in patients with high expression level of TACC3 (HR=1.90, 95% CI=1.63-2.23). In the subgroup analysis, the association was also observed in patients with cancers of digestive system (HR=1.85, 95% CI=1.53-2.24). Statistical significance was also observed in subgroup meta-analysis stratified by the cancer type, analysis type and sample size. Furthermore, poorer DFS was observed in patients with high expression level of TACC3 (HR=2.67, 95% CI=2.10-3.40). Additionally, the pooled odds ratios (ORs) showed that increased TACC3 expression was also related to positive lymph node metastasis (OR=1.68, 95% CI=1.26-2.25), tumor differentiation (OR=1.90, 95% CI=1.25-2.88) and TNM stage (OR=1.66, 95% CI=1.25-2.20). In conclusion, the increased expression level of TACC3 was associated with unfavorable prognosis, suggesting that it was a valuable prognosis biomarker or a promising therapeutic target of solid tumors. Further studies should be conducted to confirm the clinical utility of TACC3 in human solid tumors.

Regulation of paclitaxel activity by microtubule-associated proteins in cancer chemotherapy

Microtubules, highly dynamic components of the cytoskeleton, participate in diverse cellular activities such as mitosis, cell migration, and intracellular trafficking. Dysregulation of microtubule dynamics contributes to the development of serious diseases, including cancer. The dynamic properties and functions of microtubule network are regulated by microtubule-associated proteins. Paclitaxel, an anti-microtubule agent of the taxane family, has shown a success in clinical treatment of many cancer patients. However, the variable response activity of patients and acquired resistance to paclitaxel limit the clinical use of the drug. Accumulating studies show that microtubule-associated proteins can regulate paclitaxel sensitivity in a wide range of cancer types. In this review, we will describe the roles of various microtubule-associated proteins in the regulation of paclitaxel in cancers. Particularly, we will focus on the modulation of centrosomal proteins in paclitaxel resistance. Improved understandings of how these proteins act might predict treatment responses and provide insights into more rational chemotherapeutic regimens in clinical practice.

Overexpression of TACC3 is correlated with tumor aggressiveness and poor prognosis in prostate cancer

Transforming acidic coiled-coil (TACC3), a member of the TACC family, has been shown to be deregulated in various cancers and involved in tumor progression. However, its biological role and molecular mechanism in prostate cancer (PCa) have not been elucidated. Herein, we reported that TACC3 was markedly upregulated in metastatic PCa. The upregulation of TACC3 was significantly associated with the metastasis status, tumor stage, total prostate-specific antigen (PSA) level, and Gleason score in patients with PCa. Moreover, a Kaplan-Meier survival analysis showed that patients with PCa who had high TACC3 expression experienced shorter disease-free survival than patients with a low TACC3 expression. In addition, the knockdown of TACC3 dramatically reduced the migratory speed and invasiveness of PCa cells. Furthermore, silencing TACC3 markedly suppressed the Wnt/β-catenin signaling pathway. Taken together, these findings uncover a supportive role for TACC3 in PCa metastasis, which is mediated by the activation of the Wnt/β-catenin signaling pathway, suggesting that TACC3 may serve as a prognostic marker in patients with metastatic PCa.

FGFR3-TACC3 fusion in solid tumors: mini review

Fibroblast growth factor receptors (FGFR) are transmembrane kinase proteins with growing importance in cancer biology given the frequency of molecular alterations and vast interface with multiple other signaling pathways. Furthermore, numerous FGFR inhibitors in clinical development demonstrate the expanding therapeutic relevance of this pathway. Indeed, results from early phase clinical trials already indicate that a subset of patients with advanced tumors derive benefit from FGFR targeted therapies. FGFR gene aberrations and FGFR gene rearrangements are relatively rare in solid malignancies. The recently described FGFR3-TACC3 fusion protein has a constitutively active tyrosine kinase domain and promotes aneuploidy. We summarize the prevalence data on FGFR3-TACC3 fusions among different histological tumor types and the preliminary evidence that this rearrangement represents a targetable molecular aberration in some patients with solid tumors.

TACC3 promotes stemness and is a potential therapeutic target in hepatocellular carcinoma

Transforming acidic coiled-coil protein 3 (TACC3) is essential for cell mitosis and transcriptional functions. In the present study, we first demonstrated that both TACC3 protein and mRNA levels were elevated in HCC tissue samples compared with non-cancerous tissue biopsies according to western blot analyses, immunohistochemistry (IHC) and quantitative real-time PCR (qRT-PCR) assays. Moreover, high TACC3 expression was positively correlated with poor overall survival (OS) and disease-free survival (DFS) (p < 0.001). Using HCC cell lines, we then demonstrated that either TACC3 knockdown or treatment with the potential TACC3 inhibitor KHS101 suppressed cell growth and sphere formation as well as the expression of stem cell transcription factors, including Bmi1, c-Myc and Nanog. Silencing TACC3 may suppress the Wnt/β-catenin and PI3K/AKT signaling pathways, which regulate cancer stem cell-like characteristics. Taken together, these data suggest that TACC3 is enriched in HCC and that TACC3 down-regulation inhibits the proliferation, clonogenicity, and cancer stem cell-like phenotype of HCC cells. KHS101, a TACC3 inhibitor, may serve as a novel therapeutic agent for HCC patients with tumors characterized by high TACC3 expression.

Suppression of intestinal tumors by targeting the mitotic spindle of intestinal stem cells

Human colorectal cancer is often initiated by the aberrant activation of Wnt signaling, notably following adenomatous polyposis coli (Apc) inactivation. Recent studies identified adult intestinal stem cells (ISCs) and demonstrated their role as the cells of origin for intestinal tumors. However, the early consequences of aberrant Wnt signaling activation remain to be fully elucidated. Here, using organoid cultures established from conditional knockout mice and in vitro gene ablation, we show that Apc inactivation led to aberrant ISC proliferation and the expansion of the crypt domain. This system was used to evaluate the potential of a cancer-related spindle protein, Tacc3, as a target of cancer therapy, as its disruption led to the suppression of tumor formation in an animal model of intestinal tumors. We found that Tacc3 is required for the proper mitosis of Apc-deficient ISCs, and its disruption significantly attenuated the expansion of the crypt domain. In vivo analysis of corresponding mutant mice demonstrated that Tacc3 disruption led to a significant decrease in tumor number and prolonged survival. These observations demonstrated that Tacc3 is a potential chemotherapeutic target for intestinal tumors by perturbing the aberrant cell proliferation of Apc-deficient ISCs and provides an opportunity for the development of novel cancer prevention and treatment.

High expression of TACC3 in esophageal squamous cell carcinoma correlates with poor prognosis

To analyze the expression of the transforming acidic coiled-coil protein 3 (TACC3) in esophageal squamous cell carcinoma (ESCC) samples, and to identify whether TACC3 can serve as a biomarker for the diagnosis and prognosis of ESCC, qPCR, western blotting and immunohistochemistry staining (IHC) were utilized to detect the expression of TACC3. Furthermore, cell growth, colony formation, migration ability and the epithelial-mesenchymal transition markers of ESCC cells in which TACC3 were knocked-down were measured. The mRNA and protein levels of TACC3 were higher in ESCC specimens compared to non-tumorous esophageal epithelial tissues. IHC results revealed TACC3 expression was significantly correlated to differentiation (p = 0.017) and lymphoid nodal status (p = 0.028). The patients with high-expression of TACC3 had a significantly poor prognosis compared to those of low-expression (p = 0.017), especially in the patients at stages I–II (p = 0.028). Multivariate analysis indicated that TACC3 expression was an independent prognostic factor for ESCC patients (p = 0.025). Knockdown of TACC3 inhibited the ability of cell proliferation, colony formation and migration. This study first identifies TACC3 not only as a useful biomarker for diagnose and prognosis of ESCC, but also as a potential therapeutic target for patients with ESCC.

The clinical significance of transforming acidic coiled-coil protein 3 expression in non-small cell lung cancer

The relationship between TACC3, a member of the transforming acidic coiled-coil proteins (TACCs) family, and lung carcinoma remains unclear. The present study was designed to explore the prognostic and clinical significance of TACC3 in non-small cell lung cancer (NSCLC). An immunohistochemistry (IHC) assay was performed to analyze the expression of TACC3 in 195 lung cancer cases. The mRNA and protein levels of TACC3 were examined by quantitative reverse transcription-PCR or western blotting. The correlation between TACC3 expression and clinicopathological factors was analyzed by χ2 analysis and Fisher's exact test. Kaplan-Meier analysis and the Cox proportional hazards model were used to examine the correlation of prognostic outcomes with TACC3. The results showed that the levels of TACC3 mRNA and total protein were higher in lung cancer lesions than paired non-cancerous tissues. IHC analysis revealed that TACC3 was highly expressed in 94 (48.2%) cases. The expression of TACC3 was strongly correlated with smoking status, histological classification, differentiation, cytokeratin 19 fragment levels, T stage and the clinical stage of NSCLC patients. Univariate and multivariate analyses demonstrated that TACC3 is a useful biomarker for NSCLC prognosis. The low TACC3 expression group exhibited better progression-free survival (PFS) among patients who received anti-microtubule chemotherapy. In conclusion, the results showed that a high level of TACC3 expression was correlated with advanced clinicopathological classifications, poor overall survival (OS) and poor recurrence-free survival (RFS) in NSCLC patients. Our findings indicate that TACC3 is a potential prognostic marker and therapeutic target for NSCLC.

High expression of transforming acidic coiled coil-containing protein 3 strongly correlates with aggressive characteristics and poor prognosis of gastric cancer

Transforming acidic coiled coil-containing protein 3 (TACC3) is well understood to regulate mitotic spindle dynamics and centrosome integrity during mitosis. TACC3 has been suggested to be deregulated in a variety of human malignancies and may be involved in the process of cancer progression. The aim of the present study was to determine the status of TACC3 expression in gastric cancer (GC) and to clarify its clinical/prognostic significance. In the present study, we applied quantitative PCR (qPCR) and western blotting to examine TACC3 mRNA/protein expression in paired GC tissues and matched adjacent non-malignant tissues. Immunohistochemistry (IHC) was performed on a large cohort of 186 postoperative GC samples. Chi-square test, Kaplan-Meier analysis and Cox regression modelling were used to analyse the data. Upregulated mRNA and protein expression levels of TACC3 were observed in the majority of the GC tissues based on qPCR and western blotting compared to the adjacent non-cancerous gastric tissues. Specific IHC staining for TACC3 was predominantly identified in the cytoplasm of the cancer cells. A high expression of TACC3 was detected in 102 of the 186 (54.8%) tissue samples and was significantly associated with the extracapsular extension of the tumour (P<0.001), tumour relapse (P<0.001) and shortened overall survival in GC (P<0.001). Further analysis demonstrated that the TACC3 expression level stratified the patient outcome in stage II (P=0.040), stage III (P<0.001), T3/4 (P<0.001), N positive (P<0.001) and poorly differentiated/undifferentiated tumour subgroups (P<0.001). The Cox regression analysis suggested that a high expression of TACC3 was an independent prognostic factor for GC patients. The measurement of TACC3 protein expression may be beneficial for predicting clinical outcomes for GC patients.

TACC3-ch-TOG track the growing tips of microtubules independently of clathrin and Aurora-A phosphorylation

The interaction between TACC3 (transforming acidic coiled coil protein 3) and the microtubule polymerase ch-TOG (colonic, hepatic tumor overexpressed gene) is evolutionarily conserved. Loading of TACC3-ch-TOG onto mitotic spindle microtubules requires the phosphorylation of TACC3 by Aurora-A kinase and the subsequent interaction of TACC3 with clathrin to form a microtubule-binding surface. Recent work indicates that TACC3 can track the plus-ends of microtubules and modulate microtubule dynamics in non-dividing cells via its interaction with ch-TOG. Whether there is a pool of TACC3-ch-TOG that is independent of clathrin in human cells, and what is the function of this pool, are open questions. Here, we describe the molecular interaction between TACC3 and ch-TOG that permits TACC3 recruitment to the plus-ends of microtubules. This TACC3-ch-TOG pool is independent of EB1, EB3, Aurora-A phosphorylation and binding to clathrin. We also describe the distinct combinatorial subcellular pools of TACC3, ch-TOG and clathrin. TACC3 is often described as a centrosomal protein, but we show that there is no significant population of TACC3 at centrosomes. The delineation of distinct protein pools reveals a simplified view of how these proteins are organized and controlled by post-translational modification.

Suppression of centrosome protein TACC3 induces G1 arrest and cell death through activation of p38-p53-p21 stress signaling pathway

The centrosome regulates diverse cellular processes, including cell proliferation and differentiation. TACC3, a member of the human transforming acidic coiled-coil protein family, is a key centrosomal protein that is up-regulated in many cancers. Previous studies have demonstrated that TACC3 is essential for the survival of vertebrates and is involved in cell cycle regulation in human cells. However, the details of the underlying mechanisms in its cell cycle regulatory activity remain poorly understood. In this study, we showed that suppression of TACC3 expression induced G1 cell cycle arrest and triggered cell death in human cells. TACC3 depletion-induced G1 arrest and cell death were significantly reduced in cells either lacking p53 or with pharmacologically-inhibited p38, indicating that G1 arrest and cell death induction both require p53 and p38. TACC3 depletion up-regulated the levels of p53 and p21 and induced the accumulation of p53 both in the nucleus and at the centrosome. Interestingly, TACC3 depletion led to the activation of p38 and stimulated the recruitment of activated p38 to the centrosome. Depletion of TACC3 up-regulated the phosphorylation of p53 at Serine 33, a site known to be phosphorylated by p38 under cellular stress and further induced the accumulation of phosphorylated p53 to the centrosome. Loss of TACC3 affected centrosome integrity by disrupting the localization of components of the γ-tubulin ring complex at the centrosome. The results demonstrate that TACC3 depletion induces G1 arrest and cell death by activating p38-p53-p21 signaling and triggering a centrosome-mediated cellular stress response.

Cancer cell death induced by novel small molecules degrading the TACC3 protein via the ubiquitin-proteasome pathway

The selective degradation of target proteins with small molecules is a novel approach to the treatment of various diseases, including cancer. We have developed a protein knockdown system with a series of hybrid small compounds that induce the selective degradation of target proteins via the ubiquitin–proteasome pathway. In this study, we designed and synthesized novel small molecules called SNIPER(TACC3)s, which target the spindle regulatory protein transforming acidic coiled-coil-3 (TACC3). SNIPER(TACC3)s induce poly-ubiquitylation and proteasomal degradation of TACC3 and reduce the TACC3 protein level in cells. Mechanistic analysis indicated that the ubiquitin ligase APC/C^CDH1 mediates the SNIPER(TACC3)-induced degradation of TACC3. Intriguingly, SNIPER(TACC3) selectively induced cell death in cancer cells expressing a larger amount of TACC3 protein than normal cells. These results suggest that protein knockdown of TACC3 by SNIPER(TACC3) is a potential strategy for treating cancers overexpressing the TACC3 protein.

Prognosis significance of HER2 status and TACC1 expression in patients with gastric carcinoma

HER2 amplification and/or expression occurs in gastric carcinoma (GC), but the role of HER2 in the prognosis of GC remains unclear. The dysregulation of transforming acidic coiled coil 1 (TACC1), a downstream gene of HER2, is thought to be involved in the development of GC. The aim of this study was to investigate the role and relationship of HER2 and TACC1 in GC. The expression of HER2 and TACC1 was analyzed using immunohistochemistry on 129 primary resected GC patients, and HER2 amplification was additionally determined by FISH. The data on clinicopathological features and relevant prognostic factors in these patients were analyzed. The expression (3+, 2+ and 1+) and the amplification of HER2 was observed in 57 cases (44.2 %) and 25 cases (19.4 %), respectively, and the correlation between HER2 expression and amplification was strong (p < 0.001). According to the FDA criteria, 24 cases (18.6 %) would have been considered as HER2 positive. A total 62 (48.1 %) GC tissues showed positive cytoplasmic staining of TACC1. There was a significant and positive association between TACC1 and HER2. HER2 positive was significantly associated with TNM stage (p = 0.019), and TACC1 expression was significantly associated with lymph node metastasis (p = 0.004) and TNM stage (p = 0.004). TNM stage, TACC1 expression and co-positive of both HER2 and TACC1 were independent prognostic factors. TACC1 expression is an independent prognostic indicator of GC. The correlation between TACC1 expression and HER2-positive status indicated a possible synergistic regulation of the two molecules and co-positive of both HER2 and TACC1 maybe a more valuable prognostic marker.

Glucocorticoid-induced reversal of interleukin-1β-stimulated inflammatory gene expression in human oviductal cells

Studies indicate that high-grade serous ovarian carcinoma (HGSOC), the most common epithelial ovarian carcinoma histotype, originates from the fallopian tube epithelium (FTE). Risk factors for this cancer include reproductive parameters associated with lifetime ovulatory events. Ovulation is an acute inflammatory process during which the FTE is exposed to follicular fluid containing both pro- and anti-inflammatory molecules, such as interleukin-1 (IL1), tumor necrosis factor (TNF), and cortisol. Repeated exposure to inflammatory cytokines may contribute to transforming events in the FTE, with glucocorticoids exerting a protective effect. The global response of FTE cells to inflammatory cytokines or glucocorticoids has not been investigated. To examine the response of FTE cells and the ability of glucocorticoids to oppose this response, an immortalized human FTE cell line, OE-E6/E7, was treated with IL1β, dexamethasone (DEX), IL1β and DEX, or vehicle and genome-wide gene expression profiling was performed. IL1β altered the expression of 47 genes of which 17 were reversed by DEX. DEX treatment alone altered the expression of 590 genes, whereas combined DEX and IL1β treatment altered the expression of 784 genes. Network and pathway enrichment analysis indicated that many genes altered by DEX are involved in cytokine, chemokine, and cell cycle signaling, including NFκΒ target genes and interacting proteins. Quantitative real time RT-PCR studies validated the gene array data for IL8, IL23A, PI3 and TACC2 in OE-E6/E7 cells. Consistent with the array data, Western blot analysis showed increased levels of PTGS2 protein induced by IL1β that was blocked by DEX. A parallel experiment using primary cultured human FTE cells indicated similar effects on PTGS2, IL8, IL23A, PI3 and TACC2 transcripts. These findings support the hypothesis that pro-inflammatory signaling is induced in FTE cells by inflammatory mediators and raises the possibility that dysregulation of glucocorticoid signaling could contribute to increased risk for HGSOC.

TACC3 deregulates the DNA damage response and confers sensitivity to radiation and PARP inhibition

Deregulation of the transforming acidic coiled-coil protein 3 (TACC3), an important factor in the centrosome-microtubule system, has been linked to a variety of human cancer types. We have recently reported on the oncogenic potential of TACC3; however, the molecular mechanisms by which TACC3 mediates oncogenic function remain to be elucidated. In this study, we show that high levels of TACC3 lead to the accumulation of DNA double-strand breaks (DSBs) and disrupt the normal cellular response to DNA damage, at least in part, by negatively regulating the expression of ataxia telangiectasia mutated (ATM) and the subsequent DNA damage response (DDR) signaling cascade. Cells expressing high levels of TACC3 display defective checkpoints and DSB-mediated homologous recombination (HR) and non-homologous end joining (NHEJ) repair systems, leading to genomic instability. Importantly, high levels of TACC3 confer cellular sensitization to radiation and poly(ADP-ribose) polymerase (PARP) inhibition. Overall, our findings provide critical information regarding the mechanisms by which TACC3 contributes to genomic instability, potentially leading to cancer development, and suggest a novel prognostic, diagnostic and therapeutic strategy for the treatment of cancer types expressing high levels of TACC3.

Evidence for the importance of personalized molecular profiling in pancreatic cancer

OBJECTIVES

There is a growing body of evidence that targeted gene therapy holds great promise for the future treatment of cancer. A crucial step in this therapy is the accurate identification of appropriate candidate genes/pathways for targeted treatment. One approach is to identify variant genes/pathways that are significantly enriched in groups of afflicted individuals relative to control subjects. However, if there are multiple molecular pathways to the same cancer, the molecular determinants of the disease may be heterogeneous among individuals and possibly go undetected by group analyses.

METHODS

In an effort to explore this question in pancreatic cancer, we compared the most significantly differentially expressed genes/pathways between cancer and control patient samples as determined by group versus personalized analyses.

RESULTS

We found little to no overlap between genes/pathways identified by gene expression profiling using group analyses relative to those identified by personalized analyses.

CONCLUSIONS

Our results indicate that personalized and not group molecular profiling is the most appropriate approach for the identification of putative candidates for targeted gene therapy of pancreatic and perhaps other cancers with heterogeneous molecular etiology.

Impact of NPM, TFF3 and TACC1 on the prognosis of patients with primary gastric cancer

Background

NPM, TFF3 and TACC1 are molecular markers that play important roles in cell differentiation. Herein, we investigated their prognostic impact in patients with primary gastric cancer (GC) and determined whether they could be used as markers of more aggressive gastric carcinomas by detecting the extent of expression in human gastric carcinoma samples.

Methodology/Principal Findings

Tumor tissue specimens from 142 GC patients were retrospectively retrieved and immunohistochemically evaluated. Correlations between NPM, TFF3 and TACC1 over-expression and clincopathologic parameters, and their prognostic values were investigated with χ², Kaplan-Meier method, and Cox uni- and multivariate survival models. NPM, TFF3 and TACC1 expression was significantly higher in GC patients with poorly differentiated histologic type than that in patients with well differentiated histologic type. NPM expression was significantly higher in patients with hepatic metastasis or recurrence than that in patients without metastasis. TFF3 expression was significantly higher in patients with positive lymph node metastasis than that in patients with negative lymph node metastasis. Age, lymph node metastasis, and TFF3 and TACC1 over-expression were significantly correlated with low survival (P<0.05, P<0.05, P = 0.005 and P = 0.009, respectively). Multivariate analysis showed that lymph node metastasis and TFF3 and TACC1 over-expression were independent prognostic factors.

Conclusions

TFF3 and TACC1 over-expression in epithelial cells of surgically resected GC tissues was an independent predictor of short survival in GC patients. The prognosis was poorer in patients with positive expression of both TFF3 and TACC1 than that in patients with positive expression of TFF3 or TACC1 alone, or with negative expression of TFF3 and TACC1.

The centrosomal adaptor TACC3 and the microtubule polymerase chTOG interact via defined C-terminal subdomains in an Aurora-A kinase-independent manner

The cancer-associated, centrosomal adaptor protein TACC3 (transforming acidic coiled-coil 3) and its direct effector, the microtubule polymerase chTOG (colonic and hepatic tumor overexpressed gene), play a crucial function in centrosome-driven mitotic spindle assembly. It is unclear how TACC3 interacts with chTOG. Here, we show that the C-terminal TACC domain of TACC3 and a C-terminal fragment adjacent to the TOG domains of chTOG mediate the interaction between these two proteins. Interestingly, the TACC domain consists of two functionally distinct subdomains, CC1 (amino acids (aa) 414-530) and CC2 (aa 530-630). Whereas CC1 is responsible for the interaction with chTOG, CC2 performs an intradomain interaction with the central repeat region of TACC3, thereby masking the TACC domain before effector binding. Contrary to previous findings, our data clearly demonstrate that Aurora-A kinase does not regulate TACC3-chTOG complex formation, indicating that Aurora-A solely functions as a recruitment factor for the TACC3-chTOG complex to centrosomes and proximal mitotic spindles. We identified with CC1 and CC2, two functionally diverse modules within the TACC domain of TACC3 that modulate and mediate, respectively, TACC3 interaction with chTOG required for spindle assembly and microtubule dynamics during mitotic cell division.

A small compound targeting TACC3 revealed its different spatiotemporal contributions for spindle assembly in cancer cells

The mitotic spindle is assembled by the coordinated action of centrosomes and kinetochore microtubules. An evolutionally conserved protein family, transforming acidic coiled-coil (TACC), has been shown to be involved in this process. In humans, TACC3 is aberrantly expressed in a variety of human cancers, but its biological significance remains to be elucidated. Here, using a novel compound targeting TACC3, spindlactone (SPL), we show that the perturbation of TACC3 selectively inhibited the nucleation of centrosome microtubules in ovarian cancer cells. In contrast to centrosome microtubules, the kinetochore microtubules were robustly assembled, forming ectopic spindle poles that resulted in multipolar spindles. Interestingly, the extensive inhibition of TACC3 partially suppressed the nucleation of kinetochore microtubules. These dose-dependent effects of SPL were consistent with the results observed by the depletion of TACC3 and its binding partner, colonic and hepatic tumor overexpressed gene protein (TOGp). Although these proteins both have roles in the assembly of centrosome and kinetochore microtubules, their contributions were spatiotemporally different. Notably, SPL did not affect spindle assembly in normal cells. Furthermore, the oral administration of SPL significantly suppressed tumor growth in vivo. The unique mechanism of action of SPL not only enables it to be used as a tool to dissect the molecular basis of spindle assembly but also to provide a rationale for the use of TACC3 as a molecular target for cancer treatment. This rationale offers an opportunity to develop new strategies for cancer chemotherapy that overcome the limitations of microtubule toxins and expand their scope and clinical efficacy.

TACC3 is essential for EGF-mediated EMT in cervical cancer

The third member of transforming acidic coiled-coil protein (TACC) family, TACC3, has been shown to be an important player in the regulation of centrosome/microtubule dynamics during mitosis and found to be deregulated in a variety of human malignancies. Our previous studies have suggested that TACC3 may be involved in cervical cancer progression and chemoresistance, and its overexpression can induce epithelial-mesenchymal transition (EMT) by activating the phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated protein kinases (ERKs) signal transduction pathways. However, the upstream mechanisms of TACC3-mediated EMT and its functional/clinical importance in human cervical cancer remain elusive. Epidermal growth factor (EGF) has been shown to be a potent inducer of EMT in cervical cancer and associated with tumor invasion and metastasis. In this study, we found that TACC3 is overexpressed in cervical cancer and can be induced upon EGF stimulation. The induction of TACC3 by EGF is dependent on the tyrosine kinase activity of the EGF receptor (EGFR). Intriguingly, depletion of TACC3 abolishes EGF-mediated EMT, suggesting that TACC3 is required for EGF/EGFR-driven EMT process. Moreover, Snail, a key player in EGF-mediated EMT, is found to be correlated with the expression of TACC3 in cervical cancer. Collectively, our study highlights a novel function for TACC3 in EGF-mediated EMT process and suggests that targeting of TACC3 may be an attractive strategy to treat cervical cancers driven by EGF/EGFR signaling pathways.

Transforming acidic coiled-coil proteins (TACCs) in human cancer

Fine-tuned regulation of the centrosome/microtubule dynamics during mitosis is essential for faithful cell division. Thus, it is not surprising that deregulations in this dynamic network can contribute to genomic instability and tumorigenesis. Indeed, centrosome loss or amplification, spindle multipolarity and aneuploidy are often found in a majority of human malignancies, suggesting that defects in centrosome and associated microtubules may be directly or indirectly linked to cancer. Therefore, future research to identify and characterize genes required for the normal centrosome function and microtubule dynamics may help us gain insight into the complexity of cancer, and further provide new avenues for prognostic, diagnostics and therapeutic interventions. Members of the transforming acidic coiled-coil proteins (TACCs) family are emerging as important players of centrosome and microtubule-associated functions. Growing evidence indicates that TACCs are involved in the progression of certain solid tumors. Here, we will discuss our current understanding of the biological function of TACCs, their relevance to human cancer and possible implications for cancer management.

Regulating the ARNT/TACC3 axis: multiple approaches to manipulating protein/protein interactions with small molecules

For several well-documented reasons, it has been challenging to develop artificial small molecule inhibitors of protein/protein complexes. Such reagents are of particular interest for transcription factor complexes given links between their misregulation and disease. Here we report parallel approaches to identify regulators of a hypoxia signaling transcription factor complex, involving the ARNT subunit of the HIF (Hypoxia Inducible Factor) activator and the TACC3 (Transforming Acidic Coiled Coil Containing Protein 3) coactivator. In one route, we used in vitro NMR and biochemical screening to identify small molecules that selectively bind within the ARNT PAS (Per-ARNT-Sim) domain that recruits TACC3, identifying KG-548 as an ARNT/TACC3 disruptor. A parallel, cell-based screening approach previously implicated the small molecule KHS101 as an inhibitor of TACC3 signaling. Here, we show that KHS101 works indirectly on HIF complex formation by destabilizing both TACC3 and the HIF component HIF-1α. Overall, our data identify small molecule regulators for this important complex and highlight the utility of pursuing parallel strategies to develop protein/protein inhibitors.

TACC3 promotes epithelial-mesenchymal transition (EMT) through the activation of PI3K/Akt and ERK signaling pathways

Transforming acidic coiled-coil protein 3 (TACC3) is a member of the TACC family, essential for mitotic spindle dynamics and centrosome integrity during mitosis. Mounting evidence suggests that deregulation of TACC3 is associated with various types of human cancer. However, the molecular mechanisms by which TACC3 contributes to the development of cancer remain largely unknown. Here, we propose a novel mechanism by which TACC3 regulates epithelial-mesenchymal transition (EMT). By modulating the expression of TACC3, we found that overexpression of TACC3 leads to changes in cell morphology, proliferation, transforming capability, migratory/invasive behavior as well as the expression of EMT-related markers. Moreover, phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated protein kinases (ERKs) signaling pathways are critical for TACC3-mediated EMT process. Notably, depletion of TACC3 is sufficient to suppress EMT phenotype. Collectively, our findings identify TACC3 as a driver of tumorigenesis as well as an inducer of oncogenic EMT and highlight its overexpression as a potential therapeutic target for preventing EMT-associated tumor progression and invasion.

TACC2 is an androgen-responsive cell cycle regulator promoting androgen-mediated and castration-resistant growth of prostate cancer

Despite the existence of effective antiandrogen therapy for prostate cancer, the disease often progresses to castration-resistant states. Elucidation of the molecular mechanisms underlying the resistance for androgen deprivation in terms of the androgen receptor (AR)-regulated pathways is a requisite to manage castration-resistant prostate cancer (CRPC). Using a ChIP-cloning strategy, we identified functional AR binding sites (ARBS) in the genome of prostate cancer cells. We discovered that a centrosome- and microtubule-interacting gene, transforming acidic coiled-coil protein 2 (TACC2), is a novel androgen-regulated gene. We identified a functional AR-binding site (ARBS) including two canonical androgen response elements in the vicinity of TACC2 gene, in which activated hallmarks of histone modification were observed. Androgen-dependent TACC2 induction is regulated by AR, as confirmed by AR knockdown or its pharmacological inhibitor bicalutamide. Using long-term androgen-deprived cells as cellular models of CRPC, we demonstrated that TACC2 is highly expressed and contributes to hormone-refractory proliferation, as small interfering RNA-mediated knockdown of TACC2 reduced cell growth and cell cycle progression. By contrast, in TACC2-overexpressing cells, an acceleration of the cell cycle was observed. In vivo tumor formation study of prostate cancer in castrated immunocompromised mice revealed that TACC2 is a tumor-promoting factor. Notably, the clinical significance of TACC2 was demonstrated by a correlation between high TACC2 expression and poor survival rates. Taken together with the critical roles of TACC2 in the cell cycle and the biology of prostate cancer, we infer that the molecule is a potential therapeutic target in CRPC as well as hormone-sensitive prostate cancer.

MoMuLV-ts-1: A Unique Mouse Model of Retrovirus-Induced Lymphoma Transmitted by Breast Milk

Our laboratory has developed a murine model of lymphoma via breast milk transmission of MoMuLV-ts-1 (Moloney murine leukemia virus-temperature sensitive mutant-1). Uninfected offspring suckled from infected surrogate mothers become infected and develop lymphoma. Multiple gene integration sites of ts-1 into the infected mouse genome including tacc3, aurka, ndel1, tpx2, p53, and rhamm were identified, and mRNA expressions were quantitated. These genes produce centrosomal proteins, which may be involved in abnormal chromosomal segregation leading to aneuploidy or multiploidy, thus causing lymphoma. Since there is no report to date on this retroviral model leading to centrosomal abnormality, and causing lymphoma development, this is a valuable and unique model to study the centrosomal involvement in lymphomagenesis.

Disruption of Tacc3 function leads to in vivo tumor regression

The formation of the bipolar spindle is responsible for accurate chromosomal segregation during mitosis. The dynamic instability of microtubules has an important role in this process, and has been shown to be an effective target for cancer chemotherapy. Several agents that target non-microtubule mitotic proteins, including the motor protein Eg5, Aurora kinases and Polo-like kinases, are currently being developed as chemotherapeutic drugs. However, because the efficacies of these drugs remain elusive, new molecular targets that have essential roles in tumor cells are desired. Here, we provide in vivo evidence that transforming acidic coiled-coil-3 (Tacc3) is a potential target for cancer chemotherapy. Using MRI, we showed that Tacc3 loss led to the regression of mouse thymic lymphoma in vivo, which was accompanied by massive apoptosis. By contrast, normal tissues, including the thymus, showed no overt abnormalities, despite high Tacc3 expression. in vitro analysis indicated that Tacc3 depletion induced multi-polar spindle formation, which led to mitotic arrest, followed by apoptosis. Similar responses have been observed in Burkitt's lymphoma and T-ALL. These results show that Tacc3 is a vulnerable component of the spindle assembly in lymphoma cells and is a promising cancer chemotherapy target.